1. Technical Field
The present invention relates to a ball-type plunging constant velocity universal joint, which allows both an axial displacement and an angular displacement between two shafts, namely, a driving shaft and a driven shaft. These joints are used, for example, in power transmission mechanisms of automobiles or other industrial machines.
2. Background of the Invention
A constant velocity universal joint is a mechanism that, in a power transmission system of automobiles or other industrial machines, connects a rotation axis on a driving side and a rotation axis on a driven side and transmits torque at a constant angular velocity. These joints are available in both a fixed joint and a plunging joint. While the fixed joint allows only an angular displacement, the plunging joint allows both an angular displacement and an axial displacement.
Widely known as a ball-type plunging constant velocity universal joint, which uses balls as torque transmitting elements, is a double offset constant velocity universal joint (hereinafter, referred to as a DOJ). A typical DOJ uses six or eight torque transmitting balls, and a circumferential arrangement (pitch) of the torque transmitting balls is usually made with a uniform pitch for six balls (60°) or eight balls (45°).
FIG. 10 illustrates a DOJ that uses six torque transmitting balls. The DOJ has as key constituents an outer joint part 1, an inner joint part 2, torque transmitting balls 3, and a cage 4. As shown in the figure, the torque transmitting balls are arranged at a uniform pitch of 60°. Other constituents besides these torque transmitting balls, namely, the outer joint part 1, the inner joint part 2, and the cage 4, as well as track grooves 5 and 6 formed on the outer joint part 1 and the inner joint part 2, respectively, and pockets 7 provided on the cage 4, are all arranged at a uniform pitch in accordance with the above-mentioned arrangement of the torque transmitting balls 3.